1. Field of the Invention
The present invention generally relates to a semiconductor device mounting a logic device and the like that requires high-speed processing, and more particularly, to a semiconductor device incorporating a passive element such as a capacitor in a package.
2. Description of the Related Art
Generally, in a semiconductor device mounting an LSI that operates at high speed, a bypass condenser is incorporated in a package board in order to prevent variation of power supply voltage and malfunction due to high-frequency noise, and to secure stable operation in a high-speed operation area.
The bypass condenser is mounted on the package board as a different chip part from a semiconductor element that is mounted on the package board by flip chip mounting (FC mounting). In order to make the bypass condenser function effectively, it is necessary to place the bypass condenser near the semiconductor element. In many cases, the bypass condenser is placed at an opposite side of the package board with regard to the part on which the semiconductor element is mounted.
However, it is difficult to secure an area for mounting the bypass condenser on the package board close to the part where the semiconductor elements are mounted when mounting terminals for many signals and mounting terminals for power source and grounding are placed, or when a plurality of semiconductor elements are mounted on the package board as a system-in package. Accordingly, a structure is proposed in which the bypass condenser is placed inside the package board.
For example, an attempt has been made to incorporate the bypass condenser in the package board such as a glass ceramic board. However, a yield ratio may be reduced and an increase in costs may be caused since the number of wiring layers increases compared with a current situation and it is necessary to introduce a special material and a process.
As a method to solve this problem, it is conceived that a conventional board is used for the package board and only the semiconductor element requiring the bypass condenser is mounted on the package board via a redistribution board incorporating the capacitor.
However, board technology (wiring, multilayer, via forming technology) is required that can correspond to a minute electrode pad of the semiconductor element and a pitch between the electrode pads. Additionally, it is necessary to form vias so that a circuit on the redistribution board passes through to a reverse side of the redistribution board. Thus, it is substantially difficult to further reduce costs as achieving performance of a device. As a matter of course, it is necessary to structure the redistribution board as simply as possible in order to satisfy electric properties required by the semiconductor element mounted and to reduce costs.
However, when a thickness of the redistribution board becomes thin by simplifying the structure of the redistribution board, rigidity of the redistribution board is decreased. Thus, the redistribution board may be deformed or damaged easily in a manufacturing process of the semiconductor device.